Re: New sysctl entry: proc.PID.realpath

[David Holland <dholland-tech%netbsd.org@localhost>]

On Mon, Sep 07, 2015 at 11:13:35AM +0200, Joerg Sonnenberger wrote:
 > > Two nits:
 > > 
 > >  1) vnode_to_path(9) is undocumented
 > >  2) it only works if you are lucky (IIUC) - which you mostly are
 > > 
 > > The former is easy to fix, the latter IMHO is a killer before we expose
 > > this interface prominently and make debuggers depend on it. We then should
 > > also make $ORIGIN work in ld.elf_so ;-}
 > 
 > My suggestion was to just provide the filesystem id and inode number as
 > fallback. I still believe we should just turn on the code that remembers
 > the realpath on exec in first place, if you want to debug
 > something_with_a_very_very_very_very_..._very_long_name, you can always
 > override the (missing) default.

As best I recall (having tried to page the context in the past few
days) the only reason that code is disabled is so that it fails in a
way that's readily explainable (non-absolute paths) vs. arbitrarily
and capriciously.

There's another problem this thread hasn't mentioned, which is that
the result of vnode_to_path for non-directories isn't necessarily
unique or deterministic even if the object hasn't been moved about.

-- 
David A. Holland
dholland%netbsd.org@localhost